The father of New Zealand triplets killed in a mall fire in Qatar says it is "unbelievable" that the country's legal system has allowed a court hearing into the blaze to be delayed again.

The hearing into the Doha mall fire which killed 19 people, including the Wellington trio, was postponed for a fourth time due to the continuing absence of some defendants.

The two-year-old triplets - Lillie, Jackson and Willsher Weekes - were among 13 children who died in the Villaggio Mall blaze on May 28.

Their father Martin Weekes said Qatar's legal system was being made to look a joke and the delays were starting to shed an unfavourable light on the country and courts.

"Justice should be clear and swift. More importantly for us, the mockery the defendants are making of Qatar's courts is prolonging our pain and grief as we seek to find the answers as to why our beautiful children were killed," Weekes said.

An official report found the fire started in faulty wiring in a fluorescent light in a Nike store. Smoke from the fire spread rapidly into the neighbouring Gympanzee nursery, where the 13 children, four teachers and two firefighters died.

Defendants Gympanzee owner Iman Al Kuwari, the daughter of Qatar's minister of culture arts and heritage, and her husband Sheikh Ali Bin Jassim Al Thani, who is Qatar's Ambassador to Belgium, have again failed to attend the hearing, the Doha News reported.

A lawyer representing some of the victims at the overnight (NZ time) hearing asked the court to proceed without Al Kuwari, but the judges said they would send police to summon her to attend the next hearing.

The couple were thought to be out of Qatar and it was unclear whether a police order would compel either of them to court, Doha News said.

"We call upon the Qatar Government to put an end to this insult and injustice. Once again, families and representatives from our Governments attended court," Weekes said.

"We have continued to show more respect to the judicial system than some of the defendants. However, our patience is wearing thin."

The judges said they had previously sent notices, with court representatives knocking on the door of Al Kuwari's office, but had not received a response.

The new date for the hearing is November 29, which a court official said was the last time Al Kuwari could be tried ''amicably''. After that, she would lose the chance to mount a defence.